U.S. Commerce Secretary Wilbur Ross shares business interests with Russian President Vladimir Putin’s son-in-law, a connection that he failed to disclose earlier this year during his confirmation hearing for his Cabinet post, NBC News reports.

Ross’ link to Putin appears in the Paradise Papers, a leaked trove of millions of financial documents made public on Sunday by a partnership of media organizations and the International Consortium of Investigative Journalists.

Ross, a billionaire industrialist and a close friend of President Donald Trump, continues to hold a stake in a Russian shipping firm controlled by a Russian oligarch, Putin’s son-in-law, and other members of Putin’s inner circle, according to the documents.

Daniel Fried, an assistant secretary of state for European and Eurasian affairs under President George W. Bush, told the Guardian that Ross’ ties to Putin’s “cronies” could undermine U.S. sanctions on Russia.

In January, ahead of his confirmation, Ross agreed to sell some but not all of his global assets that posed a conflict of interest to his future position. He also agreed, as required by law, to recuse himself from matters in which he would have a direct financial interest.

Ross’ spokesman told The Guardian that his stake in the Russian firm would not conflict with his duties as commerce secretary and that Ross “recuses himself from any matters focused on transoceanic shipping vessels.”

Ross is only the latest high-ranking member of the Trump administration who failed to disclose ties to Russia or Russian officials.